Purification of pure disaccharide solution

ABSTRACT

The present invention pertains to a chromatographic process for separating saccharide monomers from dimers and/or saccharide trimers from dimers. The separation is effected with a cation exchange resin. If saccharide monomers are separated from saccharide dimers the cation exchange resin has a high degree of crosslinking. If the saccharide dimers are separated from saccharide trimers the cation exchange resins has a low degree of crosslinking.

The present invention pertains to a chromatographic process forseparating saccharide monomers from saccharide dimers and/or forseparating saccharide trimers from saccharide dimers.

Saccharides in the context of the present invention may either be sugarsor sugar derived alcohols. Such saccharides, and in particulardisaccharides such as maltose and maltitol, have recently attractedincreased attention as advantageous sweetening agents for various foodstuffs, as well as for other applications.

To date, a number of processes for producing saccharides, and inparticular disaccharides, are known. For example, processes forproducing maltose syrups, pure maltose as well as maltitol syrups andpure maltitol, are known. The common denominator of these processes isthat they use starch as the starting material. Commonly, starch ofvarious origins is liquefied and the thus obtained liquefied starch istreated with various enzymes so as to produce a maltose containingproduct.

Depending on the process employed, these maltose containing productsvary significantly not only in their maltose content but also in view ofthe amount of maltotriose and glucose contained therein.

In order to arrive at a useful maltose containing product, the knownprocesses proposed various purification procedures such ascrystallisation or chromatographic separation. Membrane separationprocesses have also been proposed. The products obtained after thesepurifications may then be used as they are obtained, or subjected tofurther treatment. For example, maltose containing products may, afterion exchange, be hydrogenated so as to obtain maltitol containingproducts. Depending on the purity these products must also be purifiedfurther.

U.S. Pat. No. 4,487,198, for example, discloses a process for purifyingmaltose syrup from a feed containing at least 70 wt %-DS maltose (wt%-DS as used in this description, and the claims means wt % on a drysolids basis) in addition to glucose and dextrin by way of achromatographic separation. More precisely this process uses a stronglyacidic cation exchange resin having sulphonyl groups of an alkalinemetal or alkaline earth metal form to generate five fractions from thefeed material.

The first fraction is rich in dextrin, the second fraction containsdextrin and maltose, the third fraction is rich in maltose, the fourthfraction contains maltose and glucose and the fifth fraction containsglucose. The mixed fractions, i.e. the second and fourth fractions arereturned into the column in order to eventually obtain a high maltosesyrup.

A further process for purifying maltose containing feed solutions by wayof chromatography is disclosed in U.S. Pat. No. 4,970,002. Processesleading to crystalline maltose are disclosed in U.S. Pat. No. 5,112,407and U.S. Pat. No. 4,816,445.

U.S. Pat. No. 5,462,864 discloses a process for producing high puritymaltitol, comprising the steps of liquefying starch, saccharifying theliquefied starch and reducing the product mixture obtained in thesaccharification step in order to obtain a maltitol containing product.This U.S. patent also contemplates a chromatographic purification ofboth the maltose containing product as well as the maltitol containingproduct.

A similar process for producing maltitol is disclosed in U.S. Pat. No.4,846,139. U.S. Pat. No. 4,846,139 discloses a process for thepreparation of crystalline maltitol comprising successively: catalytichydrogenation of a saccharified starch milk, a step of chromatographicfractionation of the hydrogenated syrup, crystallisation and separationof the maltitol crystals and recycling the mother liquor of thecrystallisation into the fractionation step.

While the aforementioned techniques may have their merits, there stillremains a need for further improvement. In particular, there is a strongneed to increase the maltose content especially in view of theseparation of the maltose from glucose and maltotriose. In fact, thereis a general need for improvement in the separation of disaccharidesfrom mono- and trisaccharides.

This separation is rather difficult according to known methods: sugardimers such as maltose, sugar monomers such as glucose and sugar trimerssuch as maltotriose have rather similar retention times in prior artseparation columns. In fact, this is not only true for sugar monomers,dimers and trimers, but also for saccharide monomers (like sugaralcohols), dimers and trimers in general.

Because of the similar retention times in prior art chromatographicseparations one had to compromise on the yield in order to obtain a goodpurity or visa versa. In some circumstances however, this compromise haslead to less than satisfying results, as high demands on purity entailedvery low yields and thus rather uneconomic processes.

A good example for this is the production of crystalline maltitol.Maltotritol, i.e. the hydrogenation product of maltotriose, inhibits thecrystallisation of maltitol even in small quantities. Accordingly, it isvery difficult to obtain crystalline maltitol in satisfying quantitiesin the presence of Maltotritol. Maltotritol or its precursor themaltotriose must therefore be removed to the largest possible extent.Similar difficulties have been found when crystallizing sucrose in thepresence of raffinose (sugar beet process) or in the presence ofkestoses (cane sugar process). The same problem exists also in thecellulose and hemicellulose hydrolyzates, which contain saccharides withvarious chain lengths as degradation products. Therefore, the need toremove trimers and monomers from dimmer solutions exists in general.

In light of the above, the present invention therefore aims at providingan improved process for separating saccharide dimers from monomers, andsaccharide trimers from dimers so as to obtain saccharide monomers,dimers and/or trimers with high purity in an economical process.

The process set forth in the claims solves this object. The process isbased on the recognition that, depending on the saccharides to beseparated, the degree of crosslinking of the ion exchange resin must beadjusted. Ion Exchange resin is preferably a gel type cation exchangeresin, and most preferably a gel type strong acid cation exchange resin.

The process is a column separation method, where the column fillingmaterial is ion exchange resin. The ion exchange resin can be chosenfrom a cation exchange resins (with styrene or acryl skeleton) as strongacid cation exchange resins or weak acid cation exchange resins.

The improvement achieved by the present invention resides, inparticular, in the effective separation of disaccharides or saccharidedimers from saccharide monomers, and the separation of saccharide dimersfrom trimers. At the same time the process according to the presentinvention avoids unnecessary dilution of the product fractions andthereby achieves the aforementioned advantages without sacrificing theoverall performance, i.e. purity and yield. Further advantages of thepresent invention will be apparent from the following detaileddescription.

The above object is achieved by a chromatographic process. This processmay be designed as a sequential simulated moving bed process, acontinuous simulated moving bed process, a batch chromatographic processor variants and combinations of these.

In this process a feed solution is subjected to a chromatographicseparation with the aid of a crosslinked ion exchange resin, which ispreferably a gel type cation exchange resin and most preferably a geltype strong acid cation exchange resin. If the composition of the feedsolution is such that saccharide monomers should be separated fromsaccharide dimers, then the degree of crosslinking in the cationexchange resin should be high. If the composition of the feed is suchthat saccharides dimers should be separated from saccharides trimers,then the degree of crosslinking of the cation exchange resin should below.

It should thereby be understood that a separation of saccharide monomersfrom saccharides dimers can lead to a saccharide monomer productfraction and a mixed fraction containing saccharide dimers. It can alsolead to a mixed fraction and a saccharide dimer product fraction. Such aseparation can also lead to two product fractions, namely amonosaccharide product fraction and a saccharide dimer product fraction.The same considerations apply mutatis mutandis to separating saccharidedimers and saccharides trimers. It is of course, also possible to treata feed solution comprising saccharide monomers, dimers and trimers byseparating the saccharide monomers from a mixed fraction in a first stepand then separating the dimers from the mixed fraction in a second step.Likewise, it is also possible to purify such a monomer, dimer and trimermixture by first of all separating a trimer fraction from a mixedmonomer and dimer fraction, and to fractionate the mixed monomer anddimer fraction in a second step.

A resin with a high degree of crosslinking is preferably a resin thathas a degree of crosslinking of 5 to 8%. A resin with a low degree ofcrosslinking preferably has a degree of crosslinking of 2 to 4.5%. Theterm ‘degree of crosslinking’ as used herein is defined in accordancewith H.-G. Elias, Macromoleküle, Huthig & Wepf Verlag Basel: Heidelbergand New York, 4^(th) edition, 1981.

According to this definition the degree of crosslinking means the weightratio of the crosslinkable monomers to the total monomers. It isconveniently expressed in percent.

It has surprisingly been found that the previously difficult separationsof saccharide monomers from saccharide dimers, and saccharide dimersfrom saccharide trimers can be improved dramatically when choosing acrosslinked ion exchange resin with a particular degree of crosslinking,which is preferably a gel type cation exchange resin and most preferablya gel type strong acid cation exchange resin.

That is, the separation of monomers from dimers can be made effectivelywhen using a ion exchange resin with a high degree of crosslinking,preferably a degree of crosslinking of 5 to 8%. At the same time,saccharide dimers can be separated effectively from saccharide trimerswith a ion exchange resin having a low degree of crosslinking,preferably 2 to 4.5%. Typically, such separations remove trisaccharidesby at least 75% and monomers by at least 65%. In the same context in aspecial embodiment the yield of dimers is over 85%.

It is thus a particular advantage of the process according to thepresent invention that the use of a particular crosslinked cationexchange resin for a particular starting material, i.e. a particularseparation purpose, leads to very favourable separations. The presentinvention thereby overcomes the difficulties encountered in the priorart methods. This is true both for the separation of saccharides such assugar monomers, dimers, and trimers, as well as saccharides such assugar alcohol monomers, dimers and trimers.

The feed solution for the process according to the present invention maybe any solution containing saccharide monomers, dimers and/or trimers.Usually the saccharide dimer will be the major component and preferablybe present in an amount of 65 to 85 wt %-DS (i.e. weight-% on drysubstance) in the feed solution. The amount of saccharide monomersand/or trimers contained in the feed solution is not particularlylimited. However, it is preferred if they are present in an amount thatis less than that of the saccharide dimer.

The method according to the present invention is particularly useful forseparating feed solutions containing a large amount of saccharide dimer,such as 65 to 85 wt %-DS and only minor amounts of saccharide monomersand/or trimers. The method is useful when the amount of saccharidemonomers and/or trimers is less than 10 wt %-DS and it is particularyuseful when the amount of saccharide monomers and/or trimers is 3 wt%-DS or less, preferably 2 wt %-DS or less and in particular 1.5 wt %-DSor less.

The feed solution may contain various solvents such as ethanol and/orwater. However, aqueous solutions are preferred.

Typical feeds for obtaining maltose rich fractions are feed solutionsobtained as the result of starch hydrolysis. For the purpose of thepresent invention, it is not critical what kind of starch is subjectedto hydrolysis and both amylase rich and amylopectin rich starches can beused. Common sources for such starches are potatoes, barley, corn, rice,sago, tapioca and other natural products well known in the art.

In order to produce a starch hydrolysis one typically in a first stepliquefies or gelatinises a starch slurry. This may be done according tomethods well known in the art. For example, such liquefaction can beachieved by using liquefying enzymes, acids or simply by heating thestarch slurry to elevated temperatures.

The effect of the liquefaction step is the fragmentation of the starchmolecule. The resulting fragments are then degraded further with the aidof enzymes in the subsequent saccharification step. The saccharificationstep, which may also be carried out according to methods well known inthe art, leads to a mixture comprising maltose, glucose, maltotriose andother polydextrins.

The saccharification is also typically effected enzymatically. For thispurpose, the use of β-amylases and 1.6 glycosidase such as isoamylaseand pullulanase has proven successful. The saccharification is also wellknown in the art (Starch: Chemistry and Technology Academic Press,1984).

One embodiment to utilize the invention is to produce starch hydrolyzatewith enzymes in a way, that maltose content is high but the content ofimpurities like trimers (e.g. maltotriose) and monomers (e.g. glucose)are in the low level. The chromatographic separation method of theinvention is used to remove the impurity, which exists in the higherconcentration by choosing the resin with the relevant crosslinkingdegree.

Another embodiment to utilize the invention is to apply the separationmethod to the hydrolyzate solution of cellulose and hemicellulose;cellulose hydrolyzate comprising glucose, cellobiose and cellotriose andhemicellulose hydrolyzate comprising e.g. xylose, xylobiose andxylotriose or other hemicellulose based monomers, dimers and trimers.

The method of the invention can be applied also for the separation ofsugar molasses. In case of the sugar beet molasses the saccharides areglucose, fructose as monomers, sucrose as dimer and raffinose as trimer.In case of cane sugar molasses monomers are glucose and fructose, dimeris sucrose and trimers are kestoses.

For the purpose of the present invention it was found that it isparticularly advantageous if the liquefied starch is treated as follows.

In a first step the liquefied starch is saccharified with pullulanase(e.g. Optimax® Optimalt®, dosage typically 1 l/ton-DS) and β-amylase(e.g. BBA® dosage typically 1 l/t-DS). It is also particularlyadvantageous if subsequently some low temperature α-amalyse (e.g. BAN®dosage typically 0.01 l/t-DS) is added and a final saccharification isachieved by way of the addition of maltogenic α-amylase (e.g.Maltogenase® dosage typically 1.5 l/t-DS). The incubation times betweenenzyme additions are typically 0 hour to 20 hours depending on the speedof the added enzyme.

Effecting the saccharification by way of sequential addition of theenzymes allows to avoid maltose losses. The simultaneous addition ofenzymes often leads to excess production of glucose and/or maltotriose.It is especially favourable to delay the addition of low temperatureα-amylase as this enzymes exhibits random endo-activity. Prolongedaction of this enzymes leads to the formation of uneven starch chainends, and thus to an increased formation of maltotriose as the β-amylaseaction will be stopped more often to form uneven chain ends.

Proceeding in the above described way is particular advantageous as ityields a maltose syrup with a maltose content of approx. 88 wt %-DS ormore. At the same time, the maltotriose content is 0.9 wt %-DS or less.However, it must also be noted that reaching very low maltotriose levelsrequires more enzyme or a longer process time. In practice, it maytherefore be more advantageous to compromise the maltotrioseconcentration rather than to increase the costs, by using more enzymesor allowing for a prolonged hydrolysis time.

It should also be noted that depending on the type of starch and thedegree of liquefaction of the raw material, it may be advantageous toadd pullulanase β-amylase and maltogenic α-amylase sequentially ratherthan simultaneously.

Generally speaking, it is favourable for the process according to thepresent invention to use a feed solution for the chromatographicseparation with a dry substance content of 25 to 70 wt %, especially 35to 5.5 wt %. However, the process according to the present invention isnot particularly limited in this respect.

It is also advantageous to use a feed solution with a disaccharidecontent of more than 70 wt %-DS and in particular from 75 wt % to 90 wt%-DS, or even better 75 wt % to 85 wt %-DS. However, feed solutions withdisaccharide contents outside these ranges can also be used.

The feed solution as described above is then subjected to thechromatographic process according to the present invention. As mentionedbefore, the chromatographic separation according to the presentinvention uses a crosslinked ion exchange resin preferably gel typecation exchange resin. This crosslinked cation exchange resin may eitherbe a strong or a weak acid cation exchange resin with styrene or acrylicskeleton.

Weakly acidic cation exchange resins may favourably be used e.g. for theseparation of more hydrophobic saccharides.

Weakly acid cation exchange resins are particularly useful for feedscontaining hydrophobic monosaccharides such as deoxy, methyl and anhydrosugars, as well as sugar alcohols from more hydrophilic sugars.

Most preferably, the weakly acidic cation exchange resin is used forseparating saccharides such as hexoses, including ketohexoses,aldohexoses, pentoses such as ketopentoses aldopentoses, correspondingsugars and sugar alcohols as well as mixtures thereof, e.g. glucose,fructose, rhamnose anhydrosorbitol, sorbitol, erythritol, inositol,arabinose; xylose and xylitol. Sucrose, betaine and amino acidcontaining solutions can also be separated advantageously. The weaklyacid cation exchange resin can also be used for separating anhydrosugarsfrom corresponding sugars as well as anhydrox sugar alcohols fromcorresponding sugar alcohol.

Preferably, the weakly acid ionic exchange resin is a crosslinkedacrylic resin with carboxylic functional groups for example Finex CA 16GC (8% DVB). The resin may be in the H⁺, K⁺, Na⁺, Mg²⁺, or Ca²⁺ form. Itmay also be used in other forms.

For the most part however, one will use strong acid cation exchangeresins for the separation of the saccharides. Strong acid cationexchange resins on the basis of sulphonated styrene divinyl benzenecopolymers are particularly useful in the context of the presentinvention. Examples of such resin are Finex CS 8 GC (4% DVB, particlesize 0.36 mm, manufactured by Finex Ltd., Finland) Purolite PCR 664(6.5% DVB, particle size 0.4 mm, manufactured by Purolite Co., USA) andAmberlite C 3120 (6% DVB, particle size 0.35 mm, manufactured by Rohmand Haas, USA).

These resins are advantageously used in their alkaline metal or earthalkaline metal form, whereby the alkaline metal form should beunderstood so as to include the NH₄ ⁺ form as well. Typically, resins inthe Na⁺, Ca²⁺ or Mg²⁺ forms are preferred.

As far as the amount of sulphonyl groups in the strongly acid cationexchange resins is concerned, it should be noted that usually thesulphonation of these styrene rings is close to 100%. However, lesserdegrees of sulphonation can also be used within the context of thepresent invention, provided that such resins still allow the aboveobject to be achieved.

The aforementioned resins are packed in a column which is loaded withthe feed solution. Typically, a feed solution containing 20 to 80 wt%-DS is loaded onto the column in an amount of 5 to 20 vol. % based onthe volume of the column.

The temperature at which the process according to the present inventionis performed is not particularly limited. However, it has been foundthat elevated temperatures such as temperatures of 60° C. or more leadto better results. Particularly good results are obtained attemperatures of 75° C. or more.

As the feed solutions according to the present invention are preferablyaqueous feed solutions, it is also generally favourable to work attemperatures below 100° C. The best temperature for performing thechromatographic separation according to the present invention thus fallswithin the range of 65 to 90° C. For maltose and maltitol containingsyrups the preferred temperature is 80° C. or higher.

As mentioned before, the process according to the present invention maylead to fractions rich in saccharide monomers, dimers and/or trimers.The product fractions and in particular the saccharide dimer productfractions are thereby of particularly high purity. That is suchfractions usually contain 90 to 96 wt %-DS or more product, e.g.disaccharide. At the same time, the amount of impurities e.g. saccharidemonomers and/or trimers in a disaccharide product fraction, is extremelysmall.

In as much as the present invention pertains to product fractions, itshould be borne in mind that this means a single fraction or a mixtureof 2 or more fractions rich in the respective product. It may also meanfractions from consecutive feeds as well as fractions derived fromfractions obtained in the chromatographic separation or membraneseparation process e.g. by way of concentration.

In the present invention resins different cross-linking can be used incolumns, which are operated in parallel or in series. Part of the resinbeds in parallel or serial columns can consist of resin with high or lowcrosslinking.

The following examples illustrate the invention. It should be borne inmind that the procedures, individual process steps, conditions andnumerical values indicated in these examples are representative of thepresent invention and should not be construed as limited to the specificcontext of the individual example only.

EXAMPLES Example 1 Preparation of a Low Maltotriose Feed Solution byAdding the Enzymes Simultaneously

A hot (temp>65° C.) liquefied starch solution from starch liquefyingprocess having a DE of 7,8 and a dry solids content of 25 wt % wasadjusted to a pH of 5,5 and cooled to 58° C. At this temperature fourenzymes 1,5 l/t dry solids (DS) Maltogenase™ 4000 L, 1 l/t-DS Promozyme®600 L, 1 l/t-DS beta-amylase Optimalt® BBA and 0,01 l/t-DS BAN 240L wereadded simulteneously=0 h. The composition of the solution changed asfollows: Oligo Maltotriose Maltose Glucose Sum Time wt %- wt %- wt %- wt%- wt %- h DS DS DS DS DS 2 24.71 7.50 61.49 1.44 95.14 18 12.74 3.6877.79 4.39 98.61 26 10.19 2.65 80.46 5.08 98.38 48 7.56 1.64 83.42 5.9198.52 68 5.81 0.92 85.33 6.34 98.39

This solution can be subjected to the chromatographic separation withhigh DVB-resin in order to remove glucose.

Example 2 Low Maltotriose Feed Solution by Delayed Addition of LowTemperature a-amylase

Example was repeated. However, the temperature was set to 60° C. and thedry matter content was increased from 25 to 30 wt %. In addition, adifferent pullulanase, Optimax L-1000 (Genencor) was used and Novo BAN240 L (low temperature−α-amylase) was added after 50 h from start ofsaccharification. The details and results are summarised in the tablebelow. Oligo Maltotriose Maltose Glucose Enzyme Time wt %- wt %- wt %-wt %- 0 h: h DS DS DS DS 2 12.0 7.2 72.2 1.4 18 6.1 2.8 81.3 3.4 24 5.82.0 82.8 3.8 BAN 240 L 50 4.8 0.9 87.5 4.7 72 4.7 0.5 85.3 4.9 144 4.90.1 85.8 5.4

This solution can be further treated similar than in Example 1 in orderto obtain solution with high maltose purity.

Example 3 Low Maltotriose Feed Solution by Sequential Addition ofSaccharifying Enzymes

A liquified barley starch solution having a DE of 4,6 was adjusted to 30wt %-DS and to pH 5,5 before enzyme addition. The temperature of theliquid was adjusted to 60° C. and 1 l/t DS Optimax® L-1000 pullulanase(from Genencor) was added. After 23 hours at 60° C. 1 l/t DSbeta-amylase (Optimalt® BBA from Genencor) was added. After 30 hours 1,5l/t DS maltogenic alpha-amylase (Maltogenase™ 4000 L from Novo) and 0,01l/t DS low temperature alpha-amylase (BAN 240 L from Novo) were added.In total the product was incubated for 72 hours at 60° C. Thecomposition developed as follows: >4 Maltotriose Maltose Glucoseoligomers h wt %-DS wt %-DS wt %-DS wt %-DS 24 8.77 68.61 0.38 8.85 481.20 88.87 4.21 3.52 72 0.74 90.50 4.78 3.90

This solution is preferably further purified with chromatographicseparation method with high DVB-resin to remove glucose.

Example 4 Low Glucose High Maltotriose Feed Solution

Liquefied corn starch having DE 10 was cooled to 60° C. The pH of the 25wt %-DS solution was adjusted to 5,5. Then 1 l/t DS Optimax® L-1000pullulanase (from Genencor) was added. After 24 hours 1 l/t DS Optimalt®BBA beta-amylase (from Genencor) was added. The hydrolysate wasincubated for a total of 72 hours at 60° C. The composition developed asfollows: Maltotriose Maltose Glucose >4 oligomers h wt %-DS wt %-DS wt%-DS wt %-DS 2 12.1 61.6 0.5 25.2 18 13.7 70.3 0.6 13.7 24 14.5 72.1 0.511.1 48 15.7 75.9 0.6 6.3 72 16.0 77.1 0.6 5.7

The solution is subjected to chromatographic separation with lowDVB-resin to remove maltotriose.

Example 5 High Maltose, Low Maltotriose Feed solution by Adding theEnzymes Sequentially at Higher Temperatures

Liquefied barley starch of 30 wt %-DS with a DE of 2,6 was adjusted topH 5,5 before enzyme additions. The temperature of the liquid was set to65° C. and a total of 0,4 l/t DS maltogenic alpha-amylase (Maltogenase™4000 L from Novo), 1 l/t DS beta-amylase (Optimalt® BBA from Genencor)and 1 l/t DS Optimax® L-1000 pullulanase (from Genencor) were added infour equal lots while stepwise lowering the temperature to 65, 64, 62,60° C. in 40 minutes intervals. After 12 hours 0,01 l/t DS lowtemperature alpha-amylase (BAN 240 L from Novo) was added. After 24hours 1,1 l/t DS maltogenic alpha-amylase (Maltogenase™ 4000 L fromNovo) was added. In total the product was incubated for 100 hours. Thecomposition developed as follows: >4 Maltotriose Maltose Glucoseoligomers h wt %-DS wt %-DS wt %-DS wt %-DS 2 8.14 81.03 0.83 9.98 167.34 84.73 1.56 6.36 24 6.24 85.70 2.12 5.95 48 0.95 87.97 4.69 6.39 1000.43 87.31 5.02 7.24

The solution can be subjected to chromatographic separation with highDVB-resin to remove glucose.

Example 6 Chromatographic Separation of Maltose Solution with HighGlucose Content

Starch hydrolysate (maltose hydrolysate) was subjected to achromatographic separation in a batch separation column. The separationwas performed in a pilot scale chromatographic separation column as abatch process.

The whole equipment consisted of a feed tank, a feed pump, a heatexchanger, a chromatographic separation column, product containers,pipelines for input of feed solution as well as eluent water, pipelinesfor output and flow control for the outcoming liquid.

The column with a diameter of 0,6 m was filled with a strong acid cationexchange resin. The height of the resin bed was approximately 5,2 m. Thedegree of cross-linkage was 5,5 w-% DVB and the average particle size ofthe resin was 0,35 mm. The resin was regenerated into sodium (Nat) formand a feeding device was placed at the top of the resin bed. Thetemperature of the column, feed solution and eluent water was 80° C. Theflow rate in the column was adjusted to 210 l/h.

Chromatographic separation was carried out as follows:

Step 1.

-   -   The dry substance of the feed solution was adjusted to 36 g dry        substance in 100 g of solution according to the refractive index        (RI) of the solution.        Step 2.    -   110 l of the preheated feed solution was pumped to the top of        the resin bed.        Step 3.    -   The feed solution was eluted downwards in the column by feeding        preheated deionised water to the top of the column.        Step 4.    -   The density and conductivity of the outcoming solution were        measured continuously. The outcoming solution was collected and        divided into five fractions in the following order: first        residual fraction (containing oligosaccharides), recycle        fraction (containing mostly maltose and maltotriose), maltose        rich fraction (containing most of the maltose), second recycle        fraction (containing mostly maltose and glucose) and second        residual fraction (containing mostly glucose). Both recycle        fractions were combined with the feed solution.

The amount of dry substance as well as maltose content in the feedsolution and in product fraction are presented in the table below. Theconcentration of maltose is expressed as percentage of the total drysubstance in the particular fraction. The yield of maltose in productfraction is also presented (the amount of the component in theparticular fraction in relation to the total amount of that component inall product fractions excluding recycle fractions). Oligosaccharide,maltotriose and glucose removals are also presented. Removal isexpressed as the amount of the component in residual fractions comparedto the amount of that component in residual fractions and in productfraction. Feed Maltose solution fraction DS in fraction, kg 45 25 DSg/100 g solution 36 21 Maltose wt %-DS 82 97 Maltotriose wt %-DS 1.7 0.4Glucose wt %-DS 6.1 1.9 Oligosaccharides wt %-DS 7.8 0.4 Maltose yield %97 (with recycle) Oligosaccharide removal % 94 Maltotriose removal % 69Glucose removal % 62

A resin with 5,5 w-% DVB separated well maltose from other components.Especially, the resin separated well maltose from glucose. Maltosepurity was increased by 15%-units. Maltose yield was 97%. Results areshown in FIG. 1.

Example 7 Chromatographic Separation of Maltose Solution with HighGlucose Content

Starch hydrolysate (maltose hydrolysate) was subjected to achromatographic separation in a batch separation column. The separationwas performed in a pilot scale chromatographic separation column as abatch process.

The whole equipment consisted of a feed tank, a feed pump, a heatexchanger, a chromatographic separation column, product containers,pipelines for input of feed solution as well as eluent water, pipelinesfor output and flow control for the outcoming liquid.

The column with a diameter of 0,225 m was filled with a strong acidcation exchange resin. The height of the resin bed was approximately 5,2m. The degree of cross-linkage was 4 w-% DVB and the average particlesize of the resin was 0,36 mm. The resin was regenerated into sodium(Na⁺) form and a feeding device was placed at the top of the resin bed.The temperature of the column, feed solution and eluent water was 80° C.The flow rate in the column was adjusted to 30 l/h. Chromatographicseparation was carried out as follows:

Step 1.

-   -   The dry substance of the feed solution was adjusted to 36 g dry        substance in 100 g of solution according to the refractive index        (RI) of the solution.        Step 2.    -   15 l of the preheated feed solution was pumped to the top of the        resin bed.        Step 3.    -   The feed solution was eluted downwards in the column by feeding        preheated ion-exchanged water to the top of the column.        Step 4.    -   The density and conductivity of the outcoming solution were        measured continuously. The outcoming solution was collected and        divided into five fractions in the following order: first        residual fraction (containing oligosaccharides), first recycle        fraction (containing mostly maltose and maltotriose), maltose        rich fraction (containing most of the maltose), second recycle        fraction (containing mostly maltose and glucose) and second        residual fraction (containing mostly glucose). First recycle        fraction was introduced to the front slope and second recycle        fraction to the back slope of the concentration profile of        chromatographic separation.

Yields and composition of solution (maltose purity) are calculatedsimilar than in Example 6. Feed Maltose solution fraction DS infraction, kg 6.0 2.8 DS g/100 g solution 36 16 Maltose wt %-DS 83 89Maltotriose wt %-DS 2.0 0.3 Glucose wt %-DS 6.5 9.0 Oligosaccharides wt%-DS 6.2 0.1 Maltose, yield % 84 Oligosaccharide removal % 99Maltotriose removal % 92 Glucose removal % 6.1

A resin with 4 w-% DVB separated well maltose from other components.Especially, the resin separated well maltose from oligosaccharides andmaltoriose. Maltose purity was increased by 6%-units. Maltose yield was(84%). Results are shown in FIG. 2.

Example 8 Chromatographic Separation of Fructose Run-Off

Fructose run-off from fructose crystallization of a process based onsucrose, was subjected to a chromatographic separation in a batchseparation column. The separation was performed in a pilot scalechromatographic separation column as a batch process.

The whole equipment consisted of a feed tank, a feed pump, a heatexchanger, a chromatographic separation column, product containers,pipelines for input of feed solution as well as eluent water, pipelinesfor output and flow control for the outcoming liquid.

The column with a diameter of 0,225 m was filled with a weakly acidcation exchange resin. The height of the resin bed was approximately 5,2m. The degree of cross-linkage was 8 w-% DVB and the average particlesize of the resin was 0,29 mm. The resin was regenerated into sodium(Na⁺) form and a feeding device was placed at the top of the resin bed.The temperature of the column, feed solution and eluent water was 65° C.The flow rate in the column was adjusted to 30 l/h. The pH of the resinwas adjusted to approximately 4,5 by circulating acidic 5% Na-acetatesolution through resin.

Chromatographic separation was carried out as follows:

Step 1.

-   -   The dry substance of the feed solution was adjusted to 30 g dry        substance in 100 g of solution according to the refractive index        (RI) of the solution.        Step 2.    -   18 l of the preheated feed solution was pumped to the top of the        resin bed.        Step 3.    -   The feed solution was eluted downwards in the column by feeding        preheated deionised water to the top of the column.        Step 4.    -   The density and conductivity of the outcoming solution were        measured continuously. The outcoming solution was collected and        divided into three fractions in the following order: residual        fraction (containing mostly oligo- and disaccharides), recycle        fraction (containing mostly glucose and fructose) and fructose        rich fraction (containing most of the fructose). Recycle        fraction was combined with the feed solution.

Yields and concentrations of components are calculated similar than inExample 6. Feed Fructose solution fraction DS in fraction, kg 6 4.2 DSg/100 g solution 30 10 Fructose wt %-DS 92 95 Glucose wt %-DS 2.2 1.6Oligo- and disaccharides 2.2 0.2 wt %-DS Fructose, yield % 96 Oligo- anddisaccharide 97 removal % Glucose removal % 31

A resin with 8 w-% DVB separated well fructose from other components.Especially, the resin separated well fructose from oligo- anddisaccharides. Fructose yield was 96%.

Example 9 High Maltotriose and High Glucose Feed Separations

Two different maltose hydrolysates were used. One contained more than1,5 wt %-DS maltotriose and the other contained more than 1,5 wt%-glucose. The separation was carried out with a 4,0 DVB-% resin and a5,5 DVB-% resin, respectively. The results are summarised in the tablebelow. Resin DVB-% 4.0 5.5 Feed composition (wt %-DS) Maltose 75.2 83.7Oligosaccharides 7.3 7.2 Maltotriose 13.6 1.5 Glucose 1.2 6.3 Productcomposition (wt %-DS) Maltose 91.0 91.0 Oligosaccharides 0.0 2.2Maltotriose 3.1 1.2 Glucose 2.6 2.5 Maltose recovery (%) 90 98.6 Recycleratio (%) 18.2 0.0 Oligosaccharide removal (%) 100 72.5 Maltotrioseremoval (%) 70.4 24.8 Glucose removal (%) 6.5 60.4

Example 10 Purification and Hydrogenation of Maltose Separation Product

The maltose product from chromatographic separation process was purifiedusing ion exchange as a tool. The resins in the purification step werestrong acid cation exchange resin and weak base anion exchange resin. Tetemperature during the purification was 60 degrees of centigrade andflow trough the resins was two bed volumes in hour. Feed syrup drysubstance content was 50%.

The hydrogenation was made in mixed batch autoclave at temperature of115 degrees of centigrade and at 40 bar pressure using Raney nickel as acatalyst. The catalyst load was 10% wet catalyst of batch dry substance.The hydrogenation time was four hours.

Example 11 Chromatographic Separation of Maltitol

Commercial maltitol syrup was subjected to a chromatographic separationin a batch separation column. The separation was performed in a pilotscale chromatographic separation column as a batch process.

The whole equipment consisted of a feed tank, a feed pump, a heatexchanger, a chromatographic separation column, product containers,pipelines for input of feed solution as well as eluent water, pipelinesfor output and flow control for the outcoming liquid.

The column with a diameter of 0,225 m was filled with a strong acidcation exchange resin. The height of the resin bed was approximately 5,2m. The degree of cross-linkage was 4 w-% DVB and the average particlesize of the resin was 0,36 mm. The resin was regenerated into sodium(Na⁺) form and a feeding device was placed at the top of the resin bed.The temperature of the column, feed solution and eluent water was 80° C.The flow rate in the column was adjusted to 30 l/h.

Chromatographic separation was carried out as follows:

Step 1.

-   -   The dry substance of the feed solution was adjusted to 36 g dry        substance in 100 g of solution according to the refractive index        (RI) of the solution.        Step 2.    -   15 l of the preheated feed solution was pumped to the top of the        resin bed.        Step 3.    -   The feed solution was eluted downwards in the column by feeding        preheated deionised water to the top of the column.        Step 4.    -   The density and conductivity of the outcoming solution were        measured continuously. The outcoming solution was collected and        divided into five fractions in the following order: first        residual fraction (containing oligosaccharides), recycle        fraction (containing mostly maltitol and maltotritol), maltitol        rich fraction (containing most of the maltitol), second recycle        fraction (containing mostly maltitol and sorbitol) and second        residual fraction (containing mostly, sorbitol). Both recycle        fractions were combined with the feed solution.

Yields and concentrations of components are calculated equally than inExample 6. Maltitol Feed solution fraction DS in fraction, kg 6 2.7 DSg/100 g solution 36 16 Maltitol wt %-DS 63 94 Maltotritol wt %-DS 15 2.7Sorbitol wt %-DS 3.9 0.8 Oligosaccharides wt %-DS 15 0.1 Maltitol, yield% 89 Oligosaccharide removal % 100 Maltotritol removal % 89 Sorbitolremoval % 88

A resin with 4 w-% DVB separated well maltitol from other components.Especially, the resin separated well maltitol from oligosaccharides andmaltotritol. Maltitol purity was increased by 31%-units. Maltitol yieldwas 89%.

Example 12 Chromatographic Separation of Maltitol Run-Off, Solution withLow Sorbitol Content

Maltitol run-off from maltitol crystallization was subjected to achromatographic separation in a batch separation column. The separationwas performed in a pilot scale chromatographic separation column as abatch process.

The whole equipment consisted of a feed tank, a feed pump, a heatexchanger, a chromatographic separation column, product containers,pipelines for input of feed solution as well as eluent water, pipelinesfor output and flow control for the outcoming liquid.

The column with a diameter of 0,225 m was filled with a strong acidcation exchange resin. The height of the resin bed was approximately 5,2m. The degree of cross-linkage was 4 w % DVB and the average particlesize of the resin was 0,36 mm. The resin was regenerated into sodium(Na⁺) form and a feeding device was placed at the top of the resin bed.The temperature of the column, feed solution and eluent water was 80° C.The flow rate in the column was adjusted to 30 l/h.

Chromatographic separation was carried out as follows:

Step 1.

-   -   The dry substance of the feed solution was adjusted to 36 g dry        substance in 100 g of solution according to the refractive index        (RI) of the solution.        Step 2.    -   9 liters of the preheated feed solution was pumped to the top of        the resin bed.        Step 3.    -   The feed solution was eluted downwards in the column by feeding        preheated deionised water to the top of the column.        Step 4.    -   The density and conductivity of the outcoming solution were        measured continuously. The outcoming solution was collected and        divided into five fractions in the following order: first        residual fraction (containing oligosaccharides), recycle        fraction (containing mostly maltitol and maltotritol), maltitol        rich fraction (containing most of the maltitol), second recycle        fraction (containing mostly maltitol and sorbitol) and second        residual fraction (containing mostly sorbitol). Both recycle        fractions were combined with the feed solution.

Yields and concentration of components have been calculated equally thanin Example 6. Feed Maltitol solution fraction DS in fraction, kg 3.8 2.3DS g/100 g solution 36 15 Maltitol wt %-DS 91 96 Maltotritol wt %-DS 60.6 Sorbitol wt %-DS 0.9 0.6 Oligosaccharides wt %-DS 0 0 Maltitol,yield % 93 Maltotritol removal % 91 Sorbitol removal % 67

A resin with 4 w-% DVB separated well maltitol from other components.Especially, the resin separated well maltitol from maltotritol. Maltitolpurity was increased by 5%-units. Maltitol yield was 93%.

Example 13 Maltitol Crystallization

A crystallization test was made by using about 213 kg of maltitol feedsyrup with purity 93,3% and a dry substance concentration of about 63,2wt.-%. The solution contained also sorbitol 3,0 wt %-DS, maltose 0,1 wt%-DS and maltotriol 0,4 wt %-DS.

The solution was continuously fed into a 400 liter evaporative vacuumcrystallizer (boiling pan) where it was agitated and concentrated underreduced pressure by boiling. The liquid level was kept low by adjustingthe feed rate. The seeding was made by 0,06% milled maltitol crystals atDS 78,2% at 60,2° C. (supersaturation about 1,19). After seeding thecrystal containing mass was further concentrated and agitated by boilingfor 4,3 hours at about 60° C. to DS 89,9% and the liquid level wasincreased at the same time. The temperature was controlled by pressure.Crystal size after boiling crystallization was 50-100 μm.

After boiling the mass was divided into two cooling crystallizers. Themain part of the mass was mixed at 60° C. constant temperatureovernight. Crystallization yield was 70% M/M when calculated from motherliquor sample. Final crystal size after crystallization was 100-200 μm.

Centrifugation was made 21 hours from the seeding with a laboratorycentrifuge (basket Ø 23 cm). The crystal cake assay without wash was99,7% DS and crystal yield was 66,9% DS/DS.

The rest of the boiling crystallized mass was cooled from 60° C. to 50°C. linearly during 17 hours. The crystallization yield was 76,7% M/Mwhen calculated from mother liquor sample. The crystal size aftercooling was 100-200 μm.

Centrifuging was made 28 hours from seeding with the laboratorycentrifuge (basket Ø 23 cm). The crystal cake assay without wash was97,4 wt %-DS and the crystal yield was 73,5% DS/DS. With 10% wash theassay of the cake was 98,6 wt %-DS and yield 62,2 wt % DS/DS.

1. Chromatographic process for separating saccharide monomers fromdimers and/or saccharide trimers from dimers, wherein an ion exchangeresin with a high degree of crosslinking is used when saccharidemonomers are separated from dimers and a ion exchange resin with a lowdegree of crosslinking is used when saccharide trimers are separatedfrom dimers.
 2. Process according to claim 1 wherein the resin forseparating saccharide monomers from dimers has a degree of crosslinkingof 5 to 8% and the resin for separating saccharide trimers from dimershas a degree of crosslinking of 2 to 4.5%.
 3. Process according to claim1 or claim 2 wherein the feed solution contains a saccharide dimers and2 wt %-DS or less of a saccharide monomer and/or saccharide trimer. 4.Process according to claim 1 or claim 2 wherein the feed solutioncontains saccharide dimers and 6 wt %-DS or less of saccharide monomersand/or saccharide trimers.
 5. Process according to any one of thepreceding claims wherein the saccharide dimer is maltose, maltitol orsucrose.
 6. Process according to any on of the preceeding claims whereinthe saccharide dimer is cellobiose, cellobitol, xylobiose or xylobitol.7. Process according to any one of the preceeding claims, wherein thesaccharide monomer is glucose, fructose or sorbitol.
 8. Processaccording to any one of the preceding claims wherein the crosslinkedcation exchange resin is a strong acid cation exchange resin.
 9. Processaccording to any one of the preceding claims wherein the crosslinkedcation exchange resin is a gel type strong acid cation exchange resin.10. Process according to any one of the preceding claims wherein thesaccharides are derived from starch.
 11. Process according to claim 10,wherein the saccharides are derived by saccharification of liquefiedstarch with pullulanase and beta-amylase.
 12. Process according to claim11, wherein the saccharides are derived further by treatment withmaltogenic alpha-amylase and subsequent saccharification with lowtemperature alpha amylase, optionally followed by a finalsaccharification with maltogenic alpha-amylase.
 13. Process according toany one of the preceding claims wherein the separation is effected at atemperature of 65 to 90° C.
 14. Process according to any one of thepreceding claims wherein the separation is effected at a temperature of80° C. or more.
 15. Process according to any one of the preceding claimswherein the disaccharide is a sugar alcohol which process comprises thefurther step of crystallising the sugar alcohol.
 16. Process accordingto claim 15 wherein the disaccharide sugar alcohol is maltitol.